Suspension Fault and Engine Light On: Mercedes-Benz S-Class 222 Case Study
When both the suspension fault and engine light on warnings appear on your dashboard, it can be alarming especially in a luxury vehicle like the Mercedes-Benz S-Class 222. These indicators point to potential problems not only in your vehicle’s air suspension system but possibly in the overall drivetrain or engine management.
In this case study, we break down a real customer complaint, diagnostic steps, and a detailed repair process that helped restore the performance and comfort of an S-Class 222.
Whether you’re an enthusiast or a technician, this article will help you understand how to approach suspension fault and engine light on issues effectively using Mercedes-Benz diagnostic procedures.
Vehicle Overview
- Model: Mercedes-Benz S-Class 222
- Customer Complaint: Suspension fault and engine light on
- Diagnostic Tool Used: Mercedes Xentry Diagnostic System
Initial Diagnostic: Reading the Fault Codes
The first step in addressing the issue was to run an initial diagnostic using the Xentry tool. The scan revealed a fault in the AIRMATIC suspension system, specifically a malfunction preventing proper inflation of the air suspension components.
At the same time, the engine light on signal indicated there may be additional faults in the drivetrain or secondary systems affected by the suspension’s failure (such as ride height sensors affecting engine management logic).
Step 1: Air Compressor Functionality Check
The AIRMATIC system relies on a central air compressor to deliver pressurized air to the suspension balloons. In this case, we observed the following:
- The compressor was not filling the air balloons properly, resulting in an imbalanced and uncomfortable ride.
- It was intermittently failing, suggesting internal wear or mechanical inefficiency.
- Voltage checks confirmed that the compressor was receiving correct power, so the issue was not electrical.
This confirmed the compressor unit itself was defective and needed to be replaced.
Step 2: Air Balloon Integrity Test
Upon further inspection:
- Rear air balloons had visible air leaks, leading to rapid deflation and triggering the suspension fault.
- The leaks caused an overload on the compressor, potentially worsening the situation by forcing the unit to work overtime.
The air suspension system is interdependent. A leak in one part (like a balloon) can strain others, eventually causing a system-wide failure and dashboard warnings like suspension fault and engine light on.
Final Repair and Replacement Steps
To resolve the issue comprehensively, the following parts were replaced:
New Air Balloons (Rear)
Replaced both rear suspension air springs (balloons) to eliminate leaks and restore ride height.
New Air Compressor
A new AIRMATIC compressor was installed to ensure consistent and sufficient air delivery.
New Air Filter
Helps prevent dust and contaminants from damaging the new compressor.
40 Amp Fuse + 5-Pin Relay
These were installed alongside the compressor. This is best practice when replacing compressors:
- It protects the new unit from electrical surges.
- Ensures consistent and accurate voltage supply.
- Prevents premature failure of the newly installed compressor.
Conclusion
A suspension fault and engine light on in a Mercedes-Benz S-Class 222 is not just a warning it’s a sign of critical system malfunctions that can compromise both safety and comfort. This case study highlights the importance of:
- Using the right diagnostic tools (like Xentry)
- Checking both mechanical and electrical systems
- Following best practices like fuse and relay replacement during compressor swaps
If you’re experiencing similar issues, early diagnosis and replacing worn-out parts with genuine components are key to avoiding further damage and expensive repairs.
Is it safe to drive with air suspension fault?
Driving with an air suspension fault is generally not recommended, especially in vehicles like the Mercedes-Benz S-Class that rely heavily on AIRMATIC systems for optimal handling and ride comfort.
A suspension fault can cause the vehicle to sag or sit unevenly, reducing control during turns, braking, or over bumps. This may also trigger safety features or limit performance modes.
While the car may still move, continued driving can lead to increased tire wear, damage to the compressor, or loss of handling stability. If the suspension fault and engine light are both on, it’s best to have the vehicle inspected immediately to avoid costly repairs or unsafe driving conditions.
Can a bad air suspension cause engine light to come on?
Yes, a bad air suspension can sometimes trigger the engine light to come on, especially in modern luxury vehicles like the Mercedes-Benz S-Class, where multiple control units are interconnected.
For example, if a leaking air spring or failing compressor affects the ride height sensor, it can send incorrect data to the engine or transmission control unit, leading to fault codes and illumination of the engine warning light.
Additionally, an overworked compressor may draw excess power or cause voltage irregularities, which the engine management system detects as a potential malfunction. So while not common in all cars, a failing air suspension can influence engine diagnostics in systems like the AIRMATIC-equipped S-Class.
What are common causes of air suspension failure?
Air suspension failures often stem from a combination of mechanical wear, electrical issues, and environmental exposure. In most cases, the air springs (balloons) degrade over time due to aging rubber or road debris damage, resulting in air leaks.
The air compressor may also wear out from excessive cycling or overheating, especially if it compensates for constant leaks.
Faulty ride height sensors, valve blocks, or air filters can further disrupt proper function. Corrosion or broken lines in the air tubing system can also lead to pressure drops.
For Mercedes models like the S-Class, improper voltage supply or a blown fuse/relay may cause complete suspension failure, triggering dashboard warnings and compromising vehicle stability.
What does it mean when suspension warning and engine light are both on?
When both the suspension warning and engine light are on, it suggests that the issue extends beyond just one system it may be a combined mechanical and electrical failure. In vehicles like the Mercedes-Benz S-Class, a fault in the AIRMATIC suspension (e.g., air leaks, compressor failure, sensor error) may indirectly affect engine-related control units.
This can occur through shared data lines, disrupted ride height sensors, or electrical problems that interfere with both systems. The dual warning lights indicate the vehicle’s control modules have detected errors significant enough to impact drivability or safety. It’s essential to perform a diagnostic test with tools like Xentry to identify root causes and avoid further component damage.
